function renderRootSync(root, lanes) {
    var prevExecutionContext = executionContext;
    executionContext |= RenderContext;
    var prevDispatcher = pushDispatcher(); // If the root or lanes have changed, throw out the existing stack
    // and prepare a fresh one. Otherwise we‘ll continue where we left off.

    if (workInProgressRoot !== root || workInProgressRootRenderLanes !== lanes) {
      prepareFreshStack(root, lanes);
      startWorkOnPendingInteractions(root, lanes);
    }

    var prevInteractions = pushInteractions(root);

    {
      markRenderStarted(lanes);
    }

    do {
      try {
        workLoopSync();
        break;
      } catch (thrownValue) {
        handleError(root, thrownValue);
      }
    } while (true);

    resetContextDependencies();

    {
      popInteractions(prevInteractions);
    }

    executionContext = prevExecutionContext;
    popDispatcher(prevDispatcher);

    if (workInProgress !== null) {
      // This is a sync render, so we should have finished the whole tree.
      {
        {
          throw Error( "Cannot commit an incomplete root. This error is likely caused by a bug in React. Please file an issue." );
        }
      }
    }

    {
      markRenderStopped();
    } // Set this to null to indicate there‘s no in-progress render.


    workInProgressRoot = null;
    workInProgressRootRenderLanes = NoLanes;
    return workInProgressRootExitStatus;
  }

  function workLoopSync() {
    // Already timed out, so perform work without checking if we need to yield.
    while (workInProgress !== null) {
      performUnitOfWork(workInProgress);
    }
  }

function performUnitOfWork(unitOfWork) {
    // The current, flushed, state of this fiber is the alternate. Ideally
    // nothing should rely on this, but relying on it here means that we don‘t
    // need an additional field on the work in progress.
    var current = unitOfWork.alternate;
    setCurrentFiber(unitOfWork);
    var next;

    if ( (unitOfWork.mode & ProfileMode) !== NoMode) {
      startProfilerTimer(unitOfWork);
      next = beginWork$1(current, unitOfWork, subtreeRenderLanes);
      stopProfilerTimerIfRunningAndRecordDelta(unitOfWork, true);
    } else {
      next = beginWork$1(current, unitOfWork, subtreeRenderLanes);
    }

    resetCurrentFiber();
    unitOfWork.memoizedProps = unitOfWork.pendingProps;

    if (next === null) {
      // If this doesn‘t spawn new work, complete the current work.
      completeUnitOfWork(unitOfWork);
    } else {
      workInProgress = next;
    }

    ReactCurrentOwner$2.current = null;
  }